SnapdragonCamera: Add AE_PRECAPTURE_TRIGGER_CANCEL in touch focus

1. Touch preflash usecase.
2. If Touch Preflash is completed, send AE_PRECAPTRURE_TRIGGER_CANCEL
   for only 1 frame, app only call once.
3. Reset the AE_PRECAPTURE_TRIGGER_IDLE after Step 2.

CRs-Fixed: 2338725
Change-Id: Ia890b4f05fcabbfc71be180b306146f2a806e9b8
1 file changed